<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<script>
    function js(){
        var x= 1;
        x = x + 1;
    }
   // x = x + 2;
    function js1(){
        var x = 1;
        x = x + 1;
    }
    function js2(){
        var x = 9;
        //内部函数可以访问外部函数的成员，反之则不行
        function js3(){
            var y = x + 1;
        }
        var z = y + 1;//VM70:1 Uncaught ReferenceError: z is not defined
    }
</script>
<body>


</body>
</html>